Automatic control for absorption refrigerating machines



July 18, 1 933.

AUTOMATIC CGNTROL FOR ABSORPTION REFRIGERATING MACHINES 2 Sheets-Sheet 1 Filed June 20. 1931 glwuento'c .33 Law u ahtmq w y M, D. F. KEITH 1,918,970

AUTOMATIC CONTROL FOR ABSORPTION REFRIGERATING MACHINES Filed June 20, 1931 2 Sheets-Sheet 2 m 3-. \uouk Patented July s, 1933 UNITED STATES PATENT OFFICE DAVID F. KEITH, OF CLEVELAND HEIGHTS, OHIO, ASSIGNOR TO PERFECTION STOVE COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO AUTOMATIC CONTBOI. FOR ABSORPTION REFBIGERATING MACHINES Application filed June 20,

This invention relates to an automatic control'for refrigeration apparatus of the intermittent absorption class, such, for example, as are heated by gas, in which connection it is herein disclosed, although it is not, in its broadest aspect, limited thereto.

A foremost object of the inventionis to provide a control for refrigeration apparatus of the class above referred to in WlllCh the operation is governed completely and directly by the contents of the receiver-evaporator, thereby to insure the maximum quantity of refrigerant being delivered to the receiverevaporator before the heating period is terminated, and the same being entirely exhausted before the next cycle of operation is initiated. This obviously contributes to economy of operation and promotes efficiency.

To this end I utilize the overflow of refrigerant from the receiver-evaporator, and its practically complete exhaustion therefrom, to effect, through the medium of thermostatic means, the shutting off and turning on of the heat, respectively.

Another object is to provide a safety feature by making the operativeness of the control mechanism dependent on the heat generated by the pilot light, whose primary purpose is to ignite the main burner, thereby to prevent the turning on of the gas in case the pilot light is not burning.

A further object of the invention is the provision of a very simple and economical construction that is thoroughly reliable and wherein a part of the conduit through which the refrigerant is returned from the receiverevaporator to-the generator-absorber serves as a thermostat for actuating the control mechanism.

Other objects and advantages will appear as I proceed to describe the invention in detail with reference to the accompanying drawings, wherein Fig. 1 is a diagrammatic representation of refrigeration apparatus embodying the invention; Fig. 2 is an enlarged sectional detail of the control mechanism; Fig. 3 is a view, similar to Fig. 1, of amodification; and Fig. 4 is a detail of a circulating tube used in the embodiment shown in Fig. 4.

1931. Serial No. 545,801.

In both embodiments herein disclosed, '1 designates the generator-absorber and 2 the receiver-evaporator. The latter is suitably supported in the upper portion of the refrigeration space 3 that is enclosed by the insulated walls of a cabinet 4. A tank 5 surmounts the cabinet 4 and constitutes a part of a condenser that is designatedfby the reference numeral 6. The tank 5 is adapted to contain a quantity of cooling liquid, such as water, to approximately the level indicated in the drawings.

A vapor delivery conduit 10 leads from the top (plortion of the generator-absorber 1 up war y and laterally through the wall of the tank 5, the portion of said conduit within said tank being gradually inclined upwardly toward its end where it has connec-. tion, through a pipe 11, with a coil 12 that forms another part'of the condenser 6. The lower end of the coil drains through a tube 13 into the receiver-evaporator 2. A liquid return tube 14, whose purpose will presently be explained, leads from a sump in the bottom of the receiver-evaporator 2 upwardly through a dome 15 that rises from the receiver-evaporator and thence laterally and downwardly into the generator-absorber to a point therein somewhat below the maximum liquid level in said vessel.

A burner 16 is situated below the generais adapted to be ignited. The valve 18 is carried by a bracket 25 that is secured to the adjacent end of the generator-absorber 1, and also supported by this bracket is mechanism for actuating the valve. Guided for reciprocation within a part of the bracket 25 is a rod 26 having a head 27 at its outer end. A spool-like member 28 is slidable on the rod and is urged toward the head 27 by a spring 29 that surrounds the rod and is interposed between said member and an opposed portion of the bracket 25. Pivoted to the bracket below the member 28 is a lever 30 whose lower end is disposed is operative relation to the stem 22 of the valve 18. A latch 31 is pivoted at 32 to a part of the bracket 25 adjacent the outer end of the rod 26 and the nose of said latch is adapted to cooperate with the flange at the inner end of the member 28. The latch carries an adjusting screw 33 that is adapted to be engaged by the end of the rod 26, under certain conditions, for rocking the latch on its pivot and disengaging its nose from the member Referring now to the embodiment of the invention illustrated in Fig. 1, a refrigerant return conduit 35 leads downwardly from the upper portion of the dome 15 into the body of the receiver-evaporator 2 and thence laterally through the side of said vessel and the adjacent wall of the cabinet 4 from where it is extended downwardly to the region of the lower portion of the generator-absorber 1. Here it is turned to provide a substantially horizontal branch 35 which, for convenience, and because of its function, will hereinafter be termed the thermostatic tube. Beyond this horizontal branch, to which reference has just been made, the tube or conduit is turned laterally and its end is communicatively connected to the lower portion of the generator-absorber. At a point remote from this end of the conduit that has connection with the generator-absorber, the thermostatic tube 35 is immovably fastened, as by means of a bracket 37, to the wall of the generator-absorber. Connected to the forward end of the thermostatic tube, as indicated at 38, is the inner end of the rod 26. Preferably, the portion of the refrigerant return conduit 35 between the part designated 35 and where it passes through the wall of the cabinet 4 is enclosed by an insulating jacket 39. An overflow tube 40 joins the conduit 35 at approximately the maximum liquid level in the receiver-evaporator 2.

As is commonly known, the system including the generator-absorber 1, the receiverevaporator 2, and the conduits and tubes through which these vessels communicate, is hermetically sealed and contains a quantity of a suitable absorbent,'such as water, and refrigerant, such as ammonia, in proper proportions. At the beginning of a cycle of operation, all, or practically all, of the mixture is in the generator-absorber 1. When the burner 16 is in operation, the contents of the generator-absorber boils .and the resulta'ntvapors rise through the conduit 10 and descend through the condenser coil 12 wherein they are condensed and from which they gravitate through the tube 13 to the receiverevaporator 2. All, or a large percentage, of the absorbent vapors condense within the inclined upper end of the conduit 10 and drain back into the generator-absorber. Any such vapors as pass to the coil 12 are condensed therein and travel on with the refrigerant condensate to the receiver-evaporator 2. Such absorbent condensate as remains in the evaporator-receiver at the conclusion of an evaporation period is transferred to the generator-absorber at the beginning of the next heating period through the liquid return tube 14. The principle of operation of this liquid return tube is clearly set forth in Letters Patent No. 1,816,975, dated August 4, 1931.

The liquid refrigerant continues to collect in the receiver-evaporator during the heating period until the level thereof reaches the junction between the overflow tube 40 and the refrigerant return conduit 35 when said liquid overflows and drains through said conduit and when it reaches the portion designated 35, constituting the thermostatic tube, as hereinbefore explained, said tube, by reason of its being chilled by the liquid, contracts, thus drawing inwardly the rod 26. When this happens, the head 27 of the rod moves the spool-like member 28 inwardly, permitting the lever 30 to swing in a direction to release the valve stem 22 and allow the spring 21 to seat the valve member 20 and thus shut ofi the supply of gas to the burner 16. As the apparatus is illustrated in the drawings, this stage in the cycle of operation has just been reached. Now the pressure in the system falls and the anhydrous refrigerant in the receiver-evaporator starts to evaporate and the gas returns through the conduit 35 and is absorbed by the relatively weak liquor in the generator-absorber 1. The returning gas keeps the thermostatic tube 35 cleared of liquid while the level of the mixture rises within the generator-absorber to its maximum elevation, which occurs, as is well understood, when the refrigerant is practically exhausted from the receiverevaporator. In fact, just as soon as the liquid in the receiver-evaporator drops below the end of the delivery tube 13, the pressure in the evaporator end of the system is relieved, which instantly reduces the pressure in the conduit 35 so that relatively warm liquid from the generator-absorber may flow into the thermostatic tube 35*. This warms up said tube and causes it to expand or elongate and push the rod 26 forwardly, and when the head of said rod engages the screw 33 it rocks the latch 31 on its pivot to withdraw the nose of the latch from the inner flange of the member 28 and when said member is thus released the spring 29 snaps the member 28 forwardly against the head 27 and this causes the lever 30 to be rocked in a direction to push the valve stem 22 inwardly and unseat the valve member 20, whereupon gas is supplied to the main burner and the same is ignited by the pilot light 23 and another cycle of operation begins.

The essential difference between the embodiments shown, respectively, in Figs. 1 and 3, is in the refrigerant return conduit, especially that portion associated with the generator-absorber. In the embodiment illustrated in Fig. 3, the refrigerant return conduit is designated 50 and is provided inside the receiver evaporator with an overflow tube 51. The portion of the conduit that extends downwardly alongside the cabinet ,4 is shown as enclosed by a jacket 52 of insulating material. The maximum liquid level in the generator-absorber is indicated, in Fig. 3, by the dotted line m and slightly below this level the return conduit 50 is turned forwardly to provide a horizontal branch that constitutes the thermostat tube 50*. The forward end of the tube is turned downwardly and laterally and joins the generator-absorber near the bottom thereof. Adjacent the opposite end of the generator-absorber, a branch circulation tube 52 extends through the wall of the vessel and terminates inside the same adjacent the bottom thereof, and its lower end has a restricted opening 53, as shown in Fig. 4. Adjacent the circulating tube 52, the thermostatic tube 50 is fastened, as by a bracket 54, to the wall of the generator-absorber. The forward end of the thermostatic tube is suitably connected at 55 to the rod 26. It is to be noted that the pilot light 23 is situated below the end of the refrigerant return conduit where it joins the generator-absorber; and so as to ignite the burner 16 from the pilot light, a gas communicator 56 is provided which deflects gas from the burner to the pilot light which gas is ignited and flashes back and lights that escaping from the burner. q

The operation of the present embodiment is the same as that above described excepting that, in the present case, liquid is, under certain conditions, circulated through the ther-' mostatic tube and the branch 52, such action being induced by the heat from the pilot light to which the part of the refrigerant return conduit that connects with the generator-absorber is exposed, as hereinbefore explained. By reason of the heat playing on said portion of the conduit, a thermo-siphon circulation is set up in which the liquid flows upwardly through said portion of the conduit and through-the thermostatic tube 50 and downwardly through the circulating branch 52. Such a circulation prevails so long as liquid is not excluded from the aforesaid parts by returning refrigerant, as hereinafter explained.

For the purpose of description, it will be assumed that the cycle of operation is advanced to the point where the liquid level in the receiver-evaporator has risen to the top of the overflow tube when a partof said liquid will pass through the conduit 50 and return to the generator-absorber, chilling the thermostatic tube and-thus causing it to contract and draw the rod 26 inwardly which will result, as already explained, in closing the valve 18 and shuttingv off the supply of gas to the burner. When liquid ceases to overflow from the receiver-evaporator, gas will return from said vessel through the conduit 50 and keep the circulating system, including the thermostatic tube 50, cleared of liquid. This process of evaporation-will continue until the liquid level in the generatorabsorber has risen to about the elevation in dicated by the dotted line :11 and until the liquid level in the receiver-evaporator has dropped below the end of the delivery tube 13 which will relieve the pressure in the receiver-evaporator and in the return conduit 50, whereupon liquid will flow into the conduit and the thermo-siphon circulation will again beset up under the influence of the heat from the pilot light 23. The parts are so adjusted that it requires this additional heat to cause suflicient expansion or elongation 'of the thermostatic tube 50 to project the rod 26 sufliciently to release the latch 31 and allow the member 28 to be moved by the spring 29 and rock the lever 30 in a direction to unseat the valve member 20 through the intervention of the stem 22. Consequently, under the influence of the heat stored in the liquid within the generator-absorber, augmented by that supplied by the pilot light,

the thermostatic tube functions to open the valve and set the burner in action to initiate another cycle of operation. If, however, the pilot light is accidentally or otherwise extinguished, the valve 18 will not be opened. This, therefore, provides a reliable safety feature which prevents the gas being turned on when the pilot light is not burning.

' Having thus described my invention, what I claim is 1. In an absorption refrigerating machine, a'refrigerating system including a genera to the presence of liquid in said conduit for rendering the heating means effective.

3. In an absorption refrigerating machine, a conduit communicatively connecting the generator-absorber and the receiver-evaporator and which receives liquid from the generator-absorber during a phase in the cycle of operation of the machine and is cleared of liquid by refrigerant fluid from the receiverevaporator during another phase, means for heating the generator, and mechanism responsive to the condition of said conduit for controlling the heating means;

4. In an absorption refrigerating machine, a conduit communicatively connecting the generatorabsoi'berand the receiver-evaporator and which, during one phase in the cycle of operation of the machine, contains refrigerant fluid from the receiver-evaporator and, during another phase, contains liquid from the generator-absorber, means for heating the generator-absorber, and mechanism responsive to the presence of said refrigerant fluid in the conduit for rendering the heating means ineffective, and to the presence of said liquid in the conduit for rendering the heating means effective.

5. In an absorption refrigerating machine, a conduit communicatively connecting the generator-absorber and the receiver-evaporator and which is caused to alternately expand and contract by the presence of relatively warm and cool fluids therein resulting from the normal operation of the machine, heating means for the generator-absorber, and mechanism operatively connected to said conduit for rendering the heating means effective when the conduit expands.

6. In an absorption refrigerating machine,

a conduit communicatively connecting the generator-absorber and the receiver-evaporator and which is caused to alternately expand and contract by the presence of relatively warm and cool fluids therein resulting from the normal operation of the machine, heating means for the generator-absorber, and mechanism operatively connected to said conduit for rendering the heating means ineffective when said conduit contracts.

7. In an absorption refrigerating machine, a conduit communicatively connecting the generator-absorber and the receiver-evaporator and which is caused to alternately expand and contract by the presence of relatively Warm and cool fluids therein resulting from the normal operation of the machine, heating means for the generator-absorber, and mechanism operatively connected with said conduit for rendering the heating means effective when the conduit expands and inefjfective when the conduit contracts.

8. In a absorption refrigerating machine, a conduit through which refrigerant fluid returns from the receiver-evaporator to the generator-absorber, the same contracting under the influence of relatively cool fluid therein, heating meansfor the generator-absorber and mechanism operatively connected to said conduit for rendering the heating means ineffective when the conduit expands.

9. In an absorption refrigerating machine, a conduit through which refrigerant fluid "returns from the receiver-evaporator to the generator-absorber, the same contracting under the influence of relatively cool fluid there-. in and expanding in the absence of said fluid, heating means for the generator-absorber, and mechanism operatively connected to said conduit for rendering the heating means effective when the conduit expands.

10. In an absorption refrigerating machine, in combination with the generatorabsorber' and the receiver-evaporator and the conduit through which they are communicatively connected, the two units consisting of the generator-absorber and the conduitrelatively expanding and contracting during different phases in the cycle of operation of the machine, heating means for the generator-absorber, and control mechanism for said heating means operatively connected to said units so that said heating means is rendered effective and ineffective by the relative expansion and contraction of said units.

1]. In refrigeration apparatus of themtermittent absorption class, in combination with the generator-absorber and the receiverevaporator, a conduit joining the generatorabsorber to the receiver-evaporator, said conduit entering the generator-absorber.'below its maximum liquid level, heating means for the generator-absorber, control mechanism for said heating means, and thermostatic means for governing the action of the control mechanism, said thermostatic meansinvolving that portion of said conduit which is below the maximum liquid level of the generator-absorber.

12. In refrigeration apparatus of the intermittent absorption class, a conduit through which liquid refrigerant overflows and refrigerant gas returns from the receiver-evaporator to the generator-absorber, a portion of said conduit adjacent the end connected to the generator-absorber extending in proximity to said vessel and having a part fixed against movement with respect to an adjacent part of the generator-absorber,

the portion adjacent said part being capable of expansion and contraction under the influence of different temperatures, means for heating the generator-absorber, and control mechanism for said heating means that is actuated by the expansion and contraction of the aforesaid portion of the conduit.

13. In refrigeration apparatus of the intermittent absorption class, a conduit through which liquid refrigerant overflows and refrigerant gas returns from the receiver-evaporator to the generator-absorber,

a part of said conduit being fixed against termittent absorption class, a conduit movement with respect to the generator-absorber so that a portion adjacent thereto may expand and contract with relation to the gen- 5 erator-absorber under different .temperatures, means for heating the generator-absorber, control mechanism therefor, and operative connections through which said mechanism is actuated by the expansion (and contraction of the aforesaid portionof said conduit.

14. In refrigeration apparatus of the intermittent absorption class, a conduit through which liquid refrigerant overflows from the receiver-evaporator does not prevent such flooding, means for heating the generator-absorber, control mechanism therefor, and operative connections through which said mechanism is actuated by the expansion and contraction of the aforesaid portion of said conduit;

15. In refrigeration apparatus of the intermittent absorption class, a conduit through which liquid refrigerant overflows and refrigerant gas returns from the receiver-evaporator to the generator-absorber, a part 0 said conduit being fixed against movement with respect to the generator-absorber so that a portion adjacent thereto is capable of expansion and contraction relative to the generator-absorber under different temperatures, means for heating the generator-absorber, a member movable to different positions for rendering said means effective and being biased toward the position for rendering the means ineffective, power storage means for moving said member to the position for rendering the heating means eifective, a latch for restraining the power storage means from acting, and connections through which the contraction of the aforesaid portion of said conduit stores power in said power storage means and permits said member to be moved so as to'render the heating means ineffective and whereby the expansion of said portion of the conduit releases the latch and allows said power storage means to move the member to the osition for rendering the heating means 0 ective.

16. In refrigeration apparatus of the in- .through which liquid refrigerant overflows and refrigerant gas returns from the receiver-evaporator to the generator-absorber, a branch extending from a part of said conduit remote from its connection with the gen-' erator-absorber into said vessel, a gas burner situated in heating relation tothe generator absorber, a Valve for controlling the supply of gas to the burner, a pilot light for igniting the burner and arranged in heating relation to a part of (the aforesaid conduit so that under the influence thereof a thermo-siphon circulation is set up through the portion of the conduit between its connection with the generator-absorber and the aforesaid branch and through said branch and the generatorabsorber, a part of the conduit being fixed against movement with respect to the generator-absorber so that-the aforesaid portion is capable of expanding and contracting relative to the generatonabsorber under different temperatures, control mechanism for actuating the aforesaid valve, and connections through which said mechanism is actuated by the expansion and contraction of the aforesaid portion of said conduit.

17. In refrigeration apparatus of the intermittent absorption class, a conduit through which liquid refrigerant overflows and refrigerant gas returns from the receiver-evaporator to the generator-absorber, the said conduit being'communicatively connected to the lower portion of the generator-absorber and having a portion spaced from said connection that extends substantially horizontally in proximityto the generator-absorber slightly below the plane of the maximum liquid level therein, a branch leading from a part of the conduit remote from its connection with the generator-absorber intothe same and terminating within thejlower portion thereof, the said branch having a restricted passageway relative to that of the conduit, a part of the vconduit being fixed against movement with respect to the generator-absorber whereby the section adjacent thereto is capable of expansioh and contraction relative to said vessel under different temperatures, a gas burner for heating the generator-absorber, a valve for controlling the supply of gas to the burner, a pilot light for igniting the burner and arranged in heating relation to the aforesaid conduit adjacent its connection with the generator-absorber whereby a thermo-siphon circulation is set up through the generatorabsorber and the aforesaid branch and the portion of the conduit between said branch and the point of connection between the conduit and the generator-absorber, .control mechanism for operating the aforesaid valve, and connections through which said mechanism is actuated by the expansion and con- (tiraction of the aforesaid section of the conuit.

18. In refrigeration apparatus of the intermittent-absorption class, a conduit through which liquid refrigerant overflows and refrigerant gas returns from the receiver-evaporator to the generator-absorber, the generator-absorber being in the nature of a cylindrical vessel whose longitudinal axis is substantially horizontally disposed, a portion of said conduit extending substantially horlzontally alongside the generator-absorber below the plane of the maximum liquid level therein and thence downwardly and into the lower portion of the generator-absorber at one end thereof, a branch leading from said conduit adjacent the opposite end of the generatorabsorber into said vessel and terminating near the bottom thereof, said branch having a restricted passageway with respect to that of the conduit, the horizontal portion of the conduit being connected at one end to an ad.- jacent portion of the generator-absorber so that said portion is capable of expanding and contracting in relation to said vessel under different temperatures, a gas burner for heating the generator-absorber, a valve for controlling the supply of gas thereto, a pilot light for igniting the burner and arranged in heating relation to the part of the aforesaid conduit adjacent its communicative connection with the generator-absorber whereby a thermo-siphon circulation is set up through the generator-absorber, the aforesaid branch and the portion of the said conduit between said branch and the conduits connection with the generator-absorber, control mechanism for operating the aforesaid valve, and connections through which said mechanism is actuated by the expansion and contraction of the aforesaid portion of the conduit.

19. In an intermittent absorption refrigerating machine, a generator-absorber, a receiver-evaporator, conduits joining the generator-absorber to the receiver-evaporator, said conduits having their ends liquid sealed in such manner that during the cooling phase of the refrigerating cycle the receiver-evaporator is at a higher pressure than the generator-absorber, heating means for the generator-absorber, and control mechanism arranged to render the heating means effective when the pressure in the receiver-evaporator becomes equal to the pressure in the generatorabsorber.

20. In an intermittent absorption refrigerating machine wherein a higher pressure revails in the receiver-evaporator section t an in the generator-absorber section during the cooling phase of the refrigerating cycle, heating means for the generator-absorber section, and control mechanism arranged to render the heating means effective when the pressure in the receiver-evaporator section becomes equal to the pressure in the generator-absorber section.

21. In an intermittent absorption refrigeratingmachine wherein a higher pressure prevails in the receiver-evaporator section than in the generator-absorber section during the cooling phase of the refrigerating cycle, heating means for the generator-absorber section, and control mechanism for said heating means actuated, by thevariation of the pressure difference between the generator-absorber section and the receiver-evaporator section.

22. In absorption refrigeration apparatus, means for heating the generator-absorber, thermostatic means for controlling said heating means, said thermostatic means being arranged for subjection to the temperature of the contents of the generator-absorber end of the refrigeration system, and connections whereby the pressure conditions in the system govern the subjection of said thermostatic means to said temperature.

23. In absorption refrigeration apparatus involving a generator-absorber and a receiverevaporator, means for heating the generatorabsorber, control mechanism for rendering the heating means effective to inaugurate a so-called heating period and to render it ineffective to inaugurate a so-called cooling period, means for conducting refrigerant in vaporous form from the generator-absorber and delivering it in liquid form to the receiverevaporator during the heating period, said means beingliquid sealed in the receiverevaporator when there is an appreciable quantity of liquid therein, means for returning the refrigerant in gaseous form from the receiverevaporator toward the generator-absorber during the cooling period, and thermostatic means for actuating the control mechanism arranged for subjection to the temperature of the liquid in-the generator-absorber end ofthe refrigeration system, the refrigerant return means serving by reason of a higher pressure therein to prevent such subjection until the refrigerant conducting and delivery means is unsealed in the receiver-evaporator thereby to substantially equalize the pressure throughout the system. 7 DAVID E, KEITH. 

